Bug 1614367 - Fix CMAKE_FIND_ROOT_PATH in build-clang for mac r=glandium

Best as I can tell, this was a longstanding typo. This went unnoticed because cmake didn't do any interesting `find`s -- until recently in LLVM 10, where zlib is now queried via `find_package`.

Differential Revision: https://phabricator.services.mozilla.com/D62829

--HG--
extra : moz-landing-system : lando

build/build-clang/build-clang.py

@@ -295,7 +295,7 @@ def build_one_stage(cc, cxx, asm, ld, ar, ranlib, libtool,
                 "-DCOMPILER_RT_BUILD_XRAY=OFF",
                 "-DLIBCXXABI_LIBCXX_INCLUDES=%s" % libcxx_include_dir,
                 "-DCMAKE_OSX_SYSROOT=%s" % slashify_path(os.getenv("CROSS_SYSROOT")),
-                "-DCMAKE_FIND_ROOT_PATH=%s" % slashify_path(os.getenv("CROSS_CCTOOLS_PATH")), # noqa
+                "-DCMAKE_FIND_ROOT_PATH=%s" % slashify_path(os.getenv("CROSS_SYSROOT")),
                 "-DCMAKE_FIND_ROOT_PATH_MODE_PROGRAM=NEVER",
                 "-DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY=ONLY",
                 "-DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=ONLY",